The textile industry utilizes at high speed various kinds of machinery parts for processing textile fibers. Examples of other industries using machinery parts at high speed are the paper industry, the tobacco industry, molding of parts and others. The speed at which the fibers (or other materials) move through the parts results in abrasion to the machinery parts; the parts suffer wear and degradation and must eventually be discarded. It is well known in the art that sharp-toothed wire, or the like, is used in many areas of carding, spinning, and related textile operations. In open-end spinning, for example, a sliver of separate fibers is fed into a combing roller which has metallic wires wound around the periphery of the roller, which wires are of a saw-toothed structure. The wires contact the fibers and comb them. The fibers are then transferred from the combing roller to a rotor where the combed fibers are twisted to form a yarn which is then transferred to a take-up spool. Examples of combing rollers with various toothed combing wires thereon can be found in U.S. Pat. Nos. 2,937,413; 4,233,711; 2,731,676; 4,435,952; 4,358,923; 4859,494 and 3,833,968 which patents are incorporated herein by reference. A more recent version of the wire combing roller is a homogeneous substrate of the teeth and sleeve machined from a single metal stock. An alternative device to the combing roller is a pin-ring which functions in the same way as the combing roller, but employs a multiplicity of pins extending from the roller (sleeve) rather than the toothed surface. For the purpose of this invention, the terms "combing rolls", "carding rolls" "pin-rings", and "beater rolls" (or "rollers") are used interchangeably.
These rollers are currently driven at speeds of 5,000-10,000 RPM (as described in U.S. Pat. No. 4,435,953), which cause tooth wear with time, with higher speeds expected in the future. Thus, the efficiency of the entire operation is adversely affected. Tooth wear lower the quality of the product produced over time, causing knots and neps in the yarn produced; it also causes yarn breaks, which in turn cause an individual spinning position either to shut down or to produce defective yarn.
The wire (or pins, in the case of pin-ring beater rolls) containing the teeth that do the fiber combing is generally made from steel. The wire is essentially comprised of two different parts: (1) the base of the wire, and (2) the toothed portion of the wire. Although the methods of manufacture and the specifications for the final wire or teeth vary from one manufacturer to another, it is a common practice to start with a wire initially having a round section configuration. The section configuration is modified by a process of rolling to provide a wire which is finally strip-like, with a rib running along one side to constitute a base or foundation for the finished strip (as described in U.S. Pat. No. 2,731,676). After suitable treatment which makes the wire metallurgically suitable in terms of hardness, ductility, and, hopefully, wear resistance, this base portion is then embedded in the combing roller, be it a solid piece or a sleeve.
One commonly used method for the formation of the toothed portion itself is a punching operation which imparts the shape of the tooth while also producing the proper angles for the most efficient carding and combing of a specific type of fiber.
Following the punching operation, another mechanical process used (described in U.S. Pat. No. 4,233,711) is a grinding operation. The primary function of the grinding operation is to impart an evenness to the teeth, making them all exactly uniform, as well to remove any unwanted residual defects resulting from the punching operation. As a final step, some manufacturers post treat the wire using "needle finishing" which imparts a smoothness to the sides of the teeth, along with a very light, or minimal, amount of directional lines in the steel teeth, which lines run approximately parallel to the base portion of the wire. The grinding operation also helps the efficiency of the combing operation by reducing undesired "loading" of the teeth.
Degradation of the tooth geometry occurs with use, i.e., dulling of the sharpness of the tip of the tooth and the dulling of the tooth edges which eventually leads to the general wear of the entire tooth portion of the wire. Various coatings or wire treatments, applied by the diffusion treatment process, have been devised and attempted to prevent excessive wear, or to slow down the wearing process. Examples of such coatings and wire treatment are heat treatment of carbon nitriding; surface hardening by carbon nitriding; electrospark coating (including vanadium carbide, chromium carbide, tungsten carbide, titanium carbide, zirconium carbide, hafnium carbide, and iron boride).
In still another process, a chromium layer is electrodeposited onto the teeth of the combing roll, imparting a hard chromium wear resistant layer over the steel teeth (as described in U.S. Pat. No. 4,169,019).
A more popular, and seemingly more wide-spread, method of protecting the combing teeth is by the electroless deposition of a "composite" coating. These composite coatings are usually comprised of small particles which are codeposited along with an electroless metal matrix (usually, but not limited to, a nickel-phosphorous type matrix). The wear resistant particles can range from aluminum oxides and silicon carbides, to natural and synthetic diamonds (both polycrystalline and/or monocrystalline in nature). Lubricating particles (e.g., fluorocarbon polymers, graphite flouride and others) may also be used in composite deposition. These coatings, and their like, may be applied according to the technology taught in U.S. Pat. Nos. 3,617,636; 3,940,512; 4,358,923; 4,547,407; 4,666,786; 4,419,390; Re. 29,285; 4,358,923; 4,859,494, 4,997,686; 5,195,517; 5,300,330; 4,830,889 which patents are incorporated herein by reference. A review of this composite electroless technology can be found in Chapter 11 in the text "Electroless Plating Fundamentals and Applications", G. O. Mallory and J. B. Hajdu, editors, published by the American Electroplaters and Surface Finishers Society, 1990.
In the prior art of composite plating and particularly composite electroless plating, particulate matter having the generic properties of wear resistance, lubricity, and/or corrosion resistance were advocated and used.
After the wear resistant coating is depleted, the underlying surfaces of the combing teeth degrade, and wear away with relative rapidity. Once this degradation occurs, either the combing apparatus is discarded, or the old teeth are removed and are replaced by the insertion of new teeth. These procedures are both expensive and not very cost effective. It would therefore be desirable to enable the attainment of maximum use from the protectively coated combing apparatus (or other apparatus or machinery parts) without degradation of the teeth so that the usage can be extended to multiple generations.
In commercial usage of plated molds, when deterioration of the plated articles occurs, grinding and polishing of the worn mold must sometime be effected before a new generation of plating can be undertaken. These additional mechanical operations are time consuming and costly, and hence undesirable.